Polymers can be built around a variety of different kinds of molecules. The chosen molecule becomes a template which, when removed, leaves a vacancy in the bulk polymer which is sterically and electronically selective for the template molecule. This binding site behaves like the binding site of an enzyme.
These vacancies can be filled again by reaction with the templating molecule. The resulting changes in the electronic properties of the bulk polymer may be correlated to the concentration of the template molecule in the test environment.
The prior art of which Applicant is aware may be divided into three categories: modification of electrode surfaces with the application of various polymeric materials; the templating of polymers to achieve molecular recognition; and devices for the purpose of monitoring blood or solution glucose concentrations.
The literature is replete with examples of electrodes modified with various polymeric materials. Examples of representative publications include: G. Caple et al, "Semiconducting Copolymeric Polythiophene Films", Croatia Chimica Acta, Vol. 60 (No. 3), pp. 565-568 (1987); L. Laguren-Davidson et al, "Steric Effects on the Controlled Potential Electro-Oxidation of 3-Methyl Thiophene and Thiophene Oligomers and the Properties of Their Polymer Films", Journal of the Electrochemical Society, Vol. 135 (No. 6), pp. 1406-1414 (1988); B. L. Wheeler et al, "Electrochemical Amine Sensors Using Carboxylate Functionalized Polythiophene Films", Journal of the Electrochemical Society, Vol. 136 (No. 9), pp. 2769-2770 (1989); and E. W. Tsai, "Electrochemistry of Some .beta.-Substituted Polythiophenes", Journal of the Electrochemical Society, Vol. 136 (No. 12), 3683-3689 (1989).
Examples of representative publications relating to templated polymers for molecular recognition include: G. Wulff, "Molecular Recognition in Polymers Prepared by Imprinting with Templates", ACS Symposium Series, Polymeric Reagents and Catalysts, W. T. Ford, ed., Washington, D.C., Vol. 308, pp. 186-230 (1986); G. Wulff et al, "Enzyme Analogue-Built Polymers", Makromolecular Chemie, Vol. 178, pp. 2799-2816 (1977); K. J. Shea et al, "Template Synthesis of Macromolecules. Selective Functionalization of an Organic Polymer", Journal of Organic Chemistry, Vol. 43 (No. 21), pp. 4253-4255 (1978); G. Wulff et al, "Molecular Recognition through the Exact Placement of Functional Groups on Rigid Matrices via a Template Approach", Journal of the American Chemical Society, Vol. 108 (No. 5), pp. 1089-1091 (1986); G. Wulff et al, "Enzyme-Analogue Built Polymers and Their Use for the Resolution of Racemates", Tetrahedron Letters, No. 44, pp. 4329-4332 (1973); and K. J. Shea et al, "Template Synthesis of Macromolecules. Synthesis and Chemistry of Functionalized Macroporous Polydivinylbenzene", Journal of the American Chemical Society, Vol. 102 (No. 9), pp. 3149-3155 (1980).
Almost without exception, devices intended for implant into a human for in vivo determination of glucose are based on the use of enzyme, glucose oxidase. A few, such as the following paper, are based on direct electrochemical detection of the glucose at relatively high potentials, physiologically speaking, e.g., 1 volt: S. J. Yao et al, "Low-Potential Electrochemical Redox Sensors", U.S. Pat. No. 4,805,624, issued Feb. 21, 1989.
A need remains for providing selective molecular recognition systems that act as switches, preferably at low potentials where use in the human body is concerned. One way of addressing this need would be the use of templated polymeric materials, as disclosed and claimed herein.